(a) Technical Field
The present invention relates to an apparatus and method for a neutral-position parking in a shift-by-wire system. More particularly, it relates to an apparatus and method for a neutral-position parking in a shift-by-wire system that is a sort of electronic gear transmission, which enables a more convenient parking and power-off operation at the neutral position in the shift-by-wire system.
(b) Background Art
In an automatic transmission of a shift-by-wire type, as a pressure is applied or blocked to hydraulic circuits for each step by an electric motor or a solenoid that operates according to electronic signals ordered by a transmission control unit (TCU), electronic transmission shift control is performed.
Transmission shifting in a shift-by-wire system has an advantage in that shifting manipulation to Drive (D), Reverse (R), Neutral (N), and Parking (P) positions is more conveniently performed by delivering a driver's shifting intention to a transmission control unit through simple button manipulation and lever manipulation. Also, since a transmission lever can be miniaturized, a space between a driver seat and a passenger seat increases, thereby securing an installation space for a joystick.
In a transmission operation in a typical shift-by-wire system, when an engine stops operating at the Drive (D) or Reverse (R) position, the transmission lever is automatically shifted to the parking (P) position. Accordingly, the typical shift-by-wire system provides a convenience to a driver in that a separate manipulation for shifting is not necessary.
However, a typical shift-by-wire system has the following limitation in a neutral-position parking.
FIGS. 4 and 5 are views illustrating a process of parking a vehicle mounted with a typical shift-by-wire system at the neutral position (hereinafter, referred to as N-position). First, an engine is turned off in the parking position (hereinafter, refer to as P-position). Thereafter, a release switch 30 disposed at the front of a shift-by-wire (SBW)-based transmission lever 40 is pushed in a state of stepping on a brake pedal (brake-on state) to release locking of the transmission lever, and then the transmission lever is automatically shifted to the N position by an actuator.
When an engine is turned off at the N position, the N position is maintained, and N-position parking is possible. However, since the P-position parking is desirable to prevent a vehicle from sliding at a slope, upon turning-off at the N-position, a control logic is currently applied to prevent electrical parts from being turned off and to prevent a door from being locked by a door lock/unlock actuator.
Thus, when a driver intends to perform an N-position parking, there is an inconvenience in that the engine and the electrical parts have to be turned off at the P-position, and then the release switch has to be pushed in a brake-on state to shift the transmission lever to the N position.
Also, when the transmission lever is shifted to the N position in a state where the release switch is pushed, an operation sound (e.g., buzzing or whirring sound) of an actuator that provides a shifting force to the transmission lever may become a noise.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.